/*
 * Copyright (c) 2007-2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.util;

import java.io.IOException;
import java.io.Serializable;
import java.util.Objects;

/**********************************************************************
* A class to represent a Uniform Resource Identifier (URI). This class
* is designed to handle the parsing of URIs and provide access to
* the various components (scheme, host, port, userinfo, path, query
* string and fragment) that may constitute a URI.
* <p>
* Parsing of a URI specification is done according to the URI
* syntax described in
* <a href="http://www.ietf.org/rfc/rfc2396.txt?number=2396">RFC 2396</a>,
* and amended by
* <a href="http://www.ietf.org/rfc/rfc2732.txt?number=2732">RFC 2732</a>.
* <p>
* Every absolute URI consists of a scheme, followed by a colon (':'),
* followed by a scheme-specific part. For URIs that follow the
* "generic URI" syntax, the scheme-specific part begins with two
* slashes ("//") and may be followed by an authority segment (comprised
* of user information, host, and port), path segment, query segment
* and fragment. Note that RFC 2396 no longer specifies the use of the
* parameters segment and excludes the "user:password" syntax as part of
* the authority segment. If "user:password" appears in a URI, the entire
* user/password string is stored as userinfo.
* <p>
* For URIs that do not follow the "generic URI" syntax (e.g. mailto),
* the entire scheme-specific part is treated as the "path" portion
* of the URI.
* <p>
* Note that, unlike the java.net.URL class, this class does not provide
* any built-in network access functionality nor does it provide any
* scheme-specific functionality (for example, it does not know a
* default port for a specific scheme). Rather, it only knows the
* grammar and basic set of operations that can be applied to a URI.
*
*
**********************************************************************/
public class URI implements Serializable {

    /*******************************************************************
    * MalformedURIExceptions are thrown in the process of building a URI
    * or setting fields on a URI when an operation would result in an
    * invalid URI specification.
    *
    ********************************************************************/
    public static class MalformedURIException extends IOException {

        /** Serialization version. */
        static final long serialVersionUID = -6695054834342951930L;

        /******************************************************************
         * Constructs a <code>MalformedURIException</code> with no specified
         * detail message.
         ******************************************************************/
        public MalformedURIException() {
            super();
        }

        /*****************************************************************
        * Constructs a <code>MalformedURIException</code> with the
        * specified detail message.
        *
        * @param p_msg the detail message.
        ******************************************************************/
        public MalformedURIException(String p_msg) {
            super(p_msg);
        }
    }

    /** Serialization version. */
    static final long serialVersionUID = 1601921774685357214L;

    private static final byte[] fgLookupTable = new byte[128];

    /**
     * Character Classes
     */

    /** reserved characters ;/?:@&=+$,[] */
    //RFC 2732 added '[' and ']' as reserved characters
    private static final int RESERVED_CHARACTERS = 0x01;

    /** URI punctuation mark characters: -_.!~*'() - these, combined with
        alphanumerics, constitute the "unreserved" characters */
    private static final int MARK_CHARACTERS = 0x02;

    /** scheme can be composed of alphanumerics and these characters: +-. */
    private static final int SCHEME_CHARACTERS = 0x04;

    /** userinfo can be composed of unreserved, escaped and these
        characters: ;:&=+$, */
    private static final int USERINFO_CHARACTERS = 0x08;

    /** ASCII letter characters */
    private static final int ASCII_ALPHA_CHARACTERS = 0x10;

    /** ASCII digit characters */
    private static final int ASCII_DIGIT_CHARACTERS = 0x20;

    /** ASCII hex characters */
    private static final int ASCII_HEX_CHARACTERS = 0x40;

    /** Path characters */
    private static final int PATH_CHARACTERS = 0x80;

    /** Mask for alpha-numeric characters */
    private static final int MASK_ALPHA_NUMERIC = ASCII_ALPHA_CHARACTERS | ASCII_DIGIT_CHARACTERS;

    /** Mask for unreserved characters */
    private static final int MASK_UNRESERVED_MASK = MASK_ALPHA_NUMERIC | MARK_CHARACTERS;

    /** Mask for URI allowable characters except for % */
    private static final int MASK_URI_CHARACTER = MASK_UNRESERVED_MASK | RESERVED_CHARACTERS;

    /** Mask for scheme characters */
    private static final int MASK_SCHEME_CHARACTER = MASK_ALPHA_NUMERIC | SCHEME_CHARACTERS;

    /** Mask for userinfo characters */
    private static final int MASK_USERINFO_CHARACTER = MASK_UNRESERVED_MASK | USERINFO_CHARACTERS;

    /** Mask for path characters */
    private static final int MASK_PATH_CHARACTER = MASK_UNRESERVED_MASK | PATH_CHARACTERS;

    static {
        // Add ASCII Digits and ASCII Hex Numbers
        for (int i = '0'; i <= '9'; ++i) {
            fgLookupTable[i] |= ASCII_DIGIT_CHARACTERS | ASCII_HEX_CHARACTERS;
        }

        // Add ASCII Letters and ASCII Hex Numbers
        for (int i = 'A'; i <= 'F'; ++i) {
            fgLookupTable[i] |= ASCII_ALPHA_CHARACTERS | ASCII_HEX_CHARACTERS;
            fgLookupTable[i + 0x00000020] |= ASCII_ALPHA_CHARACTERS | ASCII_HEX_CHARACTERS;
        }

        // Add ASCII Letters
        for (int i = 'G'; i <= 'Z'; ++i) {
            fgLookupTable[i] |= ASCII_ALPHA_CHARACTERS;
            fgLookupTable[i + 0x00000020] |= ASCII_ALPHA_CHARACTERS;
        }

        // Add Reserved Characters
        fgLookupTable[';'] |= RESERVED_CHARACTERS;
        fgLookupTable['/'] |= RESERVED_CHARACTERS;
        fgLookupTable['?'] |= RESERVED_CHARACTERS;
        fgLookupTable[':'] |= RESERVED_CHARACTERS;
        fgLookupTable['@'] |= RESERVED_CHARACTERS;
        fgLookupTable['&'] |= RESERVED_CHARACTERS;
        fgLookupTable['='] |= RESERVED_CHARACTERS;
        fgLookupTable['+'] |= RESERVED_CHARACTERS;
        fgLookupTable['$'] |= RESERVED_CHARACTERS;
        fgLookupTable[','] |= RESERVED_CHARACTERS;
        fgLookupTable['['] |= RESERVED_CHARACTERS;
        fgLookupTable[']'] |= RESERVED_CHARACTERS;

        // Add Mark Characters
        fgLookupTable['-'] |= MARK_CHARACTERS;
        fgLookupTable['_'] |= MARK_CHARACTERS;
        fgLookupTable['.'] |= MARK_CHARACTERS;
        fgLookupTable['!'] |= MARK_CHARACTERS;
        fgLookupTable['~'] |= MARK_CHARACTERS;
        fgLookupTable['*'] |= MARK_CHARACTERS;
        fgLookupTable['\''] |= MARK_CHARACTERS;
        fgLookupTable['('] |= MARK_CHARACTERS;
        fgLookupTable[')'] |= MARK_CHARACTERS;

        // Add Scheme Characters
        fgLookupTable['+'] |= SCHEME_CHARACTERS;
        fgLookupTable['-'] |= SCHEME_CHARACTERS;
        fgLookupTable['.'] |= SCHEME_CHARACTERS;

        // Add Userinfo Characters
        fgLookupTable[';'] |= USERINFO_CHARACTERS;
        fgLookupTable[':'] |= USERINFO_CHARACTERS;
        fgLookupTable['&'] |= USERINFO_CHARACTERS;
        fgLookupTable['='] |= USERINFO_CHARACTERS;
        fgLookupTable['+'] |= USERINFO_CHARACTERS;
        fgLookupTable['$'] |= USERINFO_CHARACTERS;
        fgLookupTable[','] |= USERINFO_CHARACTERS;

        // Add Path Characters
        fgLookupTable[';'] |= PATH_CHARACTERS;
        fgLookupTable['/'] |= PATH_CHARACTERS;
        fgLookupTable[':'] |= PATH_CHARACTERS;
        fgLookupTable['@'] |= PATH_CHARACTERS;
        fgLookupTable['&'] |= PATH_CHARACTERS;
        fgLookupTable['='] |= PATH_CHARACTERS;
        fgLookupTable['+'] |= PATH_CHARACTERS;
        fgLookupTable['$'] |= PATH_CHARACTERS;
        fgLookupTable[','] |= PATH_CHARACTERS;
    }

    /** Stores the scheme (usually the protocol) for this URI. */
    private String m_scheme = null;

    /** If specified, stores the userinfo for this URI; otherwise null */
    private String m_userinfo = null;

    /** If specified, stores the host for this URI; otherwise null */
    private String m_host = null;

    /** If specified, stores the port for this URI; otherwise -1 */
    private int m_port = -1;

    /** If specified, stores the registry based authority for this URI; otherwise -1 */
    private String m_regAuthority = null;

    /** If specified, stores the path for this URI; otherwise null */
    private String m_path = null;

    /** If specified, stores the query string for this URI; otherwise
        null.  */
    private String m_queryString = null;

    /** If specified, stores the fragment for this URI; otherwise null */
    private String m_fragment = null;

    private static boolean DEBUG = false;

    /**
    * Construct a new and uninitialized URI.
    */
    public URI() {
    }

    /**
     * Construct a new URI from another URI. All fields for this URI are
     * set equal to the fields of the URI passed in.
     *
     * @param p_other the URI to copy (cannot be null)
     */
    public URI(URI p_other) {
        initialize(p_other);
    }

    /**
     * Construct a new URI from a URI specification string. If the
     * specification follows the "generic URI" syntax, (two slashes
     * following the first colon), the specification will be parsed
     * accordingly - setting the scheme, userinfo, host,port, path, query
     * string and fragment fields as necessary. If the specification does
     * not follow the "generic URI" syntax, the specification is parsed
     * into a scheme and scheme-specific part (stored as the path) only.
     *
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty)
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                   rules
     */
    public URI(String p_uriSpec) throws MalformedURIException {
        this((URI) null, p_uriSpec);
    }

    /**
     * Construct a new URI from a URI specification string. If the
     * specification follows the "generic URI" syntax, (two slashes
     * following the first colon), the specification will be parsed
     * accordingly - setting the scheme, userinfo, host,port, path, query
     * string and fragment fields as necessary. If the specification does
     * not follow the "generic URI" syntax, the specification is parsed
     * into a scheme and scheme-specific part (stored as the path) only.
     * Construct a relative URI if boolean is assigned to "true"
     * and p_uriSpec is not valid absolute URI, instead of throwing an exception.
     *
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                            false otherwise.
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                   rules
     */
    public URI(String p_uriSpec, boolean allowNonAbsoluteURI) throws MalformedURIException {
        this((URI) null, p_uriSpec, allowNonAbsoluteURI);
    }

    /**
     * Construct a new URI from a base URI and a URI specification string.
     * The URI specification string may be a relative URI.
     *
     * @param p_base the base URI (cannot be null if p_uriSpec is null or
     *               empty)
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty if p_base is null)
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                  rules
     */
    public URI(URI p_base, String p_uriSpec) throws MalformedURIException {
        initialize(p_base, p_uriSpec);
    }

    /**
     * Construct a new URI from a base URI and a URI specification string.
     * The URI specification string may be a relative URI.
     * Construct a relative URI if boolean is assigned to "true"
     * and p_uriSpec is not valid absolute URI and p_base is null
     * instead of throwing an exception.
     *
     * @param p_base the base URI (cannot be null if p_uriSpec is null or
     *               empty)
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty if p_base is null)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                            false otherwise.
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                  rules
     */
    public URI(URI p_base, String p_uriSpec, boolean allowNonAbsoluteURI) throws MalformedURIException {
        initialize(p_base, p_uriSpec, allowNonAbsoluteURI);
    }

    /**
     * Construct a new URI that does not follow the generic URI syntax.
     * Only the scheme and scheme-specific part (stored as the path) are
     * initialized.
     *
     * @param p_scheme the URI scheme (cannot be null or empty)
     * @param p_schemeSpecificPart the scheme-specific part (cannot be
     *                             null or empty)
     *
     * @exception MalformedURIException if p_scheme violates any
     *                                  syntax rules
     */
    public URI(String p_scheme, String p_schemeSpecificPart) throws MalformedURIException {
        if (p_scheme == null || p_scheme.trim().length() == 0) {
            throw new MalformedURIException("Cannot construct URI with null/empty scheme!");
        }
        if (p_schemeSpecificPart == null || p_schemeSpecificPart.trim().length() == 0) {
            throw new MalformedURIException("Cannot construct URI with null/empty scheme-specific part!");
        }
        setScheme(p_scheme);
        setPath(p_schemeSpecificPart);
    }

    /**
     * Construct a new URI that follows the generic URI syntax from its
     * component parts. Each component is validated for syntax and some
     * basic semantic checks are performed as well.  See the individual
     * setter methods for specifics.
     *
     * @param p_scheme the URI scheme (cannot be null or empty)
     * @param p_host the hostname, IPv4 address or IPv6 reference for the URI
     * @param p_path the URI path - if the path contains '?' or '#',
     *               then the query string and/or fragment will be
     *               set from the path; however, if the query and
     *               fragment are specified both in the path and as
     *               separate parameters, an exception is thrown
     * @param p_queryString the URI query string (cannot be specified
     *                      if path is null)
     * @param p_fragment the URI fragment (cannot be specified if path
     *                   is null)
     *
     * @exception MalformedURIException if any of the parameters violates
     *                                  syntax rules or semantic rules
     */
    public URI(String p_scheme, String p_host, String p_path, String p_queryString, String p_fragment) throws MalformedURIException {
        this(p_scheme, null, p_host, -1, p_path, p_queryString, p_fragment);
    }

    /**
     * Construct a new URI that follows the generic URI syntax from its
     * component parts. Each component is validated for syntax and some
     * basic semantic checks are performed as well.  See the individual
     * setter methods for specifics.
     *
     * @param p_scheme the URI scheme (cannot be null or empty)
     * @param p_userinfo the URI userinfo (cannot be specified if host
     *                   is null)
     * @param p_host the hostname, IPv4 address or IPv6 reference for the URI
     * @param p_port the URI port (may be -1 for "unspecified"; cannot
     *               be specified if host is null)
     * @param p_path the URI path - if the path contains '?' or '#',
     *               then the query string and/or fragment will be
     *               set from the path; however, if the query and
     *               fragment are specified both in the path and as
     *               separate parameters, an exception is thrown
     * @param p_queryString the URI query string (cannot be specified
     *                      if path is null)
     * @param p_fragment the URI fragment (cannot be specified if path
     *                   is null)
     *
     * @exception MalformedURIException if any of the parameters violates
     *                                  syntax rules or semantic rules
     */
    public URI(String p_scheme, String p_userinfo, String p_host, int p_port, String p_path, String p_queryString, String p_fragment) throws MalformedURIException {
        if (p_scheme == null || p_scheme.trim().length() == 0) {
            throw new MalformedURIException("Scheme is required!");
        }

        if (p_host == null) {
            if (p_userinfo != null) {
                throw new MalformedURIException("Userinfo may not be specified if host is not specified!");
            }
            if (p_port != -1) {
                throw new MalformedURIException("Port may not be specified if host is not specified!");
            }
        }

        if (p_path != null) {
            if (p_path.indexOf('?') != -1 && p_queryString != null) {
                throw new MalformedURIException("Query string cannot be specified in path and query string!");
            }

            if (p_path.indexOf('#') != -1 && p_fragment != null) {
                throw new MalformedURIException("Fragment cannot be specified in both the path and fragment!");
            }
        }

        setScheme(p_scheme);
        setHost(p_host);
        setPort(p_port);
        setUserinfo(p_userinfo);
        setPath(p_path);
        setQueryString(p_queryString);
        setFragment(p_fragment);
    }

    /**
     * Initialize all fields of this URI from another URI.
     *
     * @param p_other the URI to copy (cannot be null)
     */
    private void initialize(URI p_other) {
        m_scheme = p_other.getScheme();
        m_userinfo = p_other.getUserinfo();
        m_host = p_other.getHost();
        m_port = p_other.getPort();
        m_regAuthority = p_other.getRegBasedAuthority();
        m_path = p_other.getPath();
        m_queryString = p_other.getQueryString();
        m_fragment = p_other.getFragment();
    }

    /**
     * Initializes this URI from a base URI and a URI specification string.
     * See RFC 2396 Section 4 and Appendix B for specifications on parsing
     * the URI and Section 5 for specifications on resolving relative URIs
     * and relative paths.
     *
     * @param p_base the base URI (may be null if p_uriSpec is an absolute
     *               URI)
     * @param p_uriSpec the URI spec string which may be an absolute or
     *                  relative URI (can only be null/empty if p_base
     *                  is not null)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                         in case of relative URI, false otherwise.
     *
     * @exception MalformedURIException if p_base is null and p_uriSpec
     *                                  is not an absolute URI or if
     *                                  p_uriSpec violates syntax rules
     */
    private void initialize(URI p_base, String p_uriSpec, boolean allowNonAbsoluteURI) throws MalformedURIException {

        String uriSpec = p_uriSpec;
        int uriSpecLen = (uriSpec != null) ? uriSpec.length() : 0;

        if (p_base == null && uriSpecLen == 0) {
            if (allowNonAbsoluteURI) {
                m_path = "";
                return;
            }
            throw new MalformedURIException("Cannot initialize URI with empty parameters.");
        }

        // just make a copy of the base if spec is empty
        if (uriSpecLen == 0) {
            initialize(p_base);
            return;
        }

        int index = 0;

        // Check for scheme, which must be before '/', '?' or '#'.
        int colonIdx = uriSpec.indexOf(':');
        if (colonIdx != -1) {
            final int searchFrom = colonIdx - 1;
            // search backwards starting from character before ':'.
            int slashIdx = uriSpec.lastIndexOf('/', searchFrom);
            int queryIdx = uriSpec.lastIndexOf('?', searchFrom);
            int fragmentIdx = uriSpec.lastIndexOf('#', searchFrom);

            if (colonIdx == 0 || slashIdx != -1 || queryIdx != -1 || fragmentIdx != -1) {
                // A standalone base is a valid URI according to spec
                if (colonIdx == 0 || (p_base == null && fragmentIdx != 0 && !allowNonAbsoluteURI)) {
                    throw new MalformedURIException("No scheme found in URI.");
                }
            } else {
                initializeScheme(uriSpec);
                index = m_scheme.length() + 1;

                // Neither 'scheme:' or 'scheme:#fragment' are valid URIs.
                if (colonIdx == uriSpecLen - 1 || uriSpec.charAt(colonIdx + 1) == '#') {
                    throw new MalformedURIException("Scheme specific part cannot be empty.");
                }
            }
        } else if (p_base == null && uriSpec.indexOf('#') != 0 && !allowNonAbsoluteURI) {
            throw new MalformedURIException("No scheme found in URI.");
        }

        // Two slashes means we may have authority, but definitely means we're either
        // matching net_path or abs_path. These two productions are ambiguous in that
        // every net_path (except those containing an IPv6Reference) is an abs_path.
        // RFC 2396 resolves this ambiguity by applying a greedy left most matching rule.
        // Try matching net_path first, and if that fails we don't have authority so
        // then attempt to match abs_path.
        //
        // net_path = "//" authority [ abs_path ]
        // abs_path = "/"  path_segments
        if (((index + 1) < uriSpecLen) && (uriSpec.charAt(index) == '/' && uriSpec.charAt(index + 1) == '/')) {
            index += 2;
            int startPos = index;

            // Authority will be everything up to path, query or fragment
            char testChar = '\0';
            while (index < uriSpecLen) {
                testChar = uriSpec.charAt(index);
                if (testChar == '/' || testChar == '?' || testChar == '#') {
                    break;
                }
                index++;
            }

            // Attempt to parse authority. If the section is an empty string
            // this is a valid server based authority, so set the host to this
            // value.
            if (index > startPos) {
                // If we didn't find authority we need to back up. Attempt to
                // match against abs_path next.
                if (!initializeAuthority(uriSpec.substring(startPos, index))) {
                    index = startPos - 2;
                }
            } else {
                m_host = "";
            }
        }

        initializePath(uriSpec, index);

        // Resolve relative URI to base URI - see RFC 2396 Section 5.2
        // In some cases, it might make more sense to throw an exception
        // (when scheme is specified is the string spec and the base URI
        // is also specified, for example), but we're just following the
        // RFC specifications
        if (p_base != null) {
            absolutize(p_base);
        }
    }

    /**
     * Initializes this URI from a base URI and a URI specification string.
     * See RFC 2396 Section 4 and Appendix B for specifications on parsing
     * the URI and Section 5 for specifications on resolving relative URIs
     * and relative paths.
     *
     * @param p_base the base URI (may be null if p_uriSpec is an absolute
     *               URI)
     * @param p_uriSpec the URI spec string which may be an absolute or
     *                  relative URI (can only be null/empty if p_base
     *                  is not null)
     *
     * @exception MalformedURIException if p_base is null and p_uriSpec
     *                                  is not an absolute URI or if
     *                                  p_uriSpec violates syntax rules
     */
    private void initialize(URI p_base, String p_uriSpec) throws MalformedURIException {

        String uriSpec = p_uriSpec;
        int uriSpecLen = (uriSpec != null) ? uriSpec.length() : 0;

        if (p_base == null && uriSpecLen == 0) {
            throw new MalformedURIException("Cannot initialize URI with empty parameters.");
        }

        // just make a copy of the base if spec is empty
        if (uriSpecLen == 0) {
            initialize(p_base);
            return;
        }

        int index = 0;

        // Check for scheme, which must be before '/', '?' or '#'.
        int colonIdx = uriSpec.indexOf(':');
        if (colonIdx != -1) {
            final int searchFrom = colonIdx - 1;
            // search backwards starting from character before ':'.
            int slashIdx = uriSpec.lastIndexOf('/', searchFrom);
            int queryIdx = uriSpec.lastIndexOf('?', searchFrom);
            int fragmentIdx = uriSpec.lastIndexOf('#', searchFrom);

            if (colonIdx == 0 || slashIdx != -1 || queryIdx != -1 || fragmentIdx != -1) {
                // A standalone base is a valid URI according to spec
                if (colonIdx == 0 || (p_base == null && fragmentIdx != 0)) {
                    throw new MalformedURIException("No scheme found in URI.");
                }
            } else {
                initializeScheme(uriSpec);
                index = m_scheme.length() + 1;

                // Neither 'scheme:' or 'scheme:#fragment' are valid URIs.
                if (colonIdx == uriSpecLen - 1 || uriSpec.charAt(colonIdx + 1) == '#') {
                    throw new MalformedURIException("Scheme specific part cannot be empty.");
                }
            }
        } else if (p_base == null && uriSpec.indexOf('#') != 0) {
            throw new MalformedURIException("No scheme found in URI.");
        }

        // Two slashes means we may have authority, but definitely means we're either
        // matching net_path or abs_path. These two productions are ambiguous in that
        // every net_path (except those containing an IPv6Reference) is an abs_path.
        // RFC 2396 resolves this ambiguity by applying a greedy left most matching rule.
        // Try matching net_path first, and if that fails we don't have authority so
        // then attempt to match abs_path.
        //
        // net_path = "//" authority [ abs_path ]
        // abs_path = "/"  path_segments
        if (((index + 1) < uriSpecLen) && (uriSpec.charAt(index) == '/' && uriSpec.charAt(index + 1) == '/')) {
            index += 2;
            int startPos = index;

            // Authority will be everything up to path, query or fragment
            char testChar = '\0';
            while (index < uriSpecLen) {
                testChar = uriSpec.charAt(index);
                if (testChar == '/' || testChar == '?' || testChar == '#') {
                    break;
                }
                index++;
            }

            // Attempt to parse authority. If the section is an empty string
            // this is a valid server based authority, so set the host to this
            // value.
            if (index > startPos) {
                // If we didn't find authority we need to back up. Attempt to
                // match against abs_path next.
                if (!initializeAuthority(uriSpec.substring(startPos, index))) {
                    index = startPos - 2;
                }
            } else if (index < uriSpecLen) {
                //Same as java.net.URI:
                // DEVIATION: Allow empty authority prior to non-empty
                // path, query component or fragment identifier
                m_host = "";
            } else {
                throw new MalformedURIException("Expected authority.");
            }
        }

        initializePath(uriSpec, index);

        // Resolve relative URI to base URI - see RFC 2396 Section 5.2
        // In some cases, it might make more sense to throw an exception
        // (when scheme is specified is the string spec and the base URI
        // is also specified, for example), but we're just following the
        // RFC specifications
        if (p_base != null) {
            absolutize(p_base);
        }
    }

    /**
     * Absolutize URI with given base URI.
     *
     * @param p_base base URI for absolutization
     */
    public void absolutize(URI p_base) {

        // check to see if this is the current doc - RFC 2396 5.2 #2
        // note that this is slightly different from the RFC spec in that
        // we don't include the check for query string being null
        // - this handles cases where the urispec is just a query
        // string or a fragment (e.g. "?y" or "#s") -
        // see <http://www.ics.uci.edu/~fielding/url/test1.html> which
        // identified this as a bug in the RFC
        if (m_path.length() == 0 && m_scheme == null && m_host == null && m_regAuthority == null) {
            m_scheme = p_base.getScheme();
            m_userinfo = p_base.getUserinfo();
            m_host = p_base.getHost();
            m_port = p_base.getPort();
            m_regAuthority = p_base.getRegBasedAuthority();
            m_path = p_base.getPath();

            if (m_queryString == null) {
                m_queryString = p_base.getQueryString();

                if (m_fragment == null) {
                    m_fragment = p_base.getFragment();
                }
            }
            return;
        }

        // check for scheme - RFC 2396 5.2 #3
        // if we found a scheme, it means absolute URI, so we're done
        if (m_scheme == null) {
            m_scheme = p_base.getScheme();
        } else {
            return;
        }

        // check for authority - RFC 2396 5.2 #4
        // if we found a host, then we've got a network path, so we're done
        if (m_host == null && m_regAuthority == null) {
            m_userinfo = p_base.getUserinfo();
            m_host = p_base.getHost();
            m_port = p_base.getPort();
            m_regAuthority = p_base.getRegBasedAuthority();
        } else {
            return;
        }

        // check for absolute path - RFC 2396 5.2 #5
        if (m_path.length() > 0 && m_path.startsWith("/")) {
            return;
        }

        // if we get to this point, we need to resolve relative path
        // RFC 2396 5.2 #6
        String path = "";
        String basePath = p_base.getPath();

        // 6a - get all but the last segment of the base URI path
        if (basePath != null && basePath.length() > 0) {
            int lastSlash = basePath.lastIndexOf('/');
            if (lastSlash != -1) {
                path = basePath.substring(0, lastSlash + 1);
            }
        } else if (m_path.length() > 0) {
            path = "/";
        }

        // 6b - append the relative URI path
        path = path.concat(m_path);

        // 6c - remove all "./" where "." is a complete path segment
        int index = -1;
        while ((index = path.indexOf("/./")) != -1) {
            path = path.substring(0, index + 1).concat(path.substring(index + 3));
        }

        // 6d - remove "." if path ends with "." as a complete path segment
        if (path.endsWith("/.")) {
            path = path.substring(0, path.length() - 1);
        }

        // 6e - remove all "<segment>/../" where "<segment>" is a complete
        // path segment not equal to ".."
        index = 1;
        int segIndex = -1;
        String tempString = null;

        while ((index = path.indexOf("/../", index)) > 0) {
            tempString = path.substring(0, path.indexOf("/../"));
            segIndex = tempString.lastIndexOf('/');
            if (segIndex != -1) {
                if (!tempString.substring(segIndex).equals("..")) {
                    path = path.substring(0, segIndex + 1).concat(path.substring(index + 4));
                    index = segIndex;
                } else {
                    index += 4;
                }
            } else {
                index += 4;
            }
        }

        // 6f - remove ending "<segment>/.." where "<segment>" is a
        // complete path segment
        if (path.endsWith("/..")) {
            tempString = path.substring(0, path.length() - 3);
            segIndex = tempString.lastIndexOf('/');
            if (segIndex != -1) {
                path = path.substring(0, segIndex + 1);
            }
        }
        m_path = path;
    }

    /**
     * Initialize the scheme for this URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     *
     * @exception MalformedURIException if URI does not have a conformant
     *                                  scheme
     */
    private void initializeScheme(String p_uriSpec) throws MalformedURIException {
        int uriSpecLen = p_uriSpec.length();
        int index = 0;
        String scheme = null;
        char testChar = '\0';

        while (index < uriSpecLen) {
            testChar = p_uriSpec.charAt(index);
            if (testChar == ':' || testChar == '/' || testChar == '?' || testChar == '#') {
                break;
            }
            index++;
        }
        scheme = p_uriSpec.substring(0, index);

        if (scheme.length() == 0) {
            throw new MalformedURIException("No scheme found in URI.");
        } else {
            setScheme(scheme);
        }
    }

    /**
     * Initialize the authority (either server or registry based)
     * for this URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     *
     * @return true if the given string matched server or registry
     * based authority
     */
    private boolean initializeAuthority(String p_uriSpec) {

        int index = 0;
        int start = 0;
        int end = p_uriSpec.length();

        char testChar = '\0';
        String userinfo = null;

        // userinfo is everything up to @
        if (p_uriSpec.indexOf('@', start) != -1) {
            while (index < end) {
                testChar = p_uriSpec.charAt(index);
                if (testChar == '@') {
                    break;
                }
                index++;
            }
            userinfo = p_uriSpec.substring(start, index);
            index++;
        }

        // host is everything up to last ':', or up to
        // and including ']' if followed by ':'.
        String host = null;
        start = index;
        boolean hasPort = false;
        if (index < end) {
            if (p_uriSpec.charAt(start) == '[') {
                int bracketIndex = p_uriSpec.indexOf(']', start);
                index = (bracketIndex != -1) ? bracketIndex : end;
                if (index + 1 < end && p_uriSpec.charAt(index + 1) == ':') {
                    ++index;
                    hasPort = true;
                } else {
                    index = end;
                }
            } else {
                int colonIndex = p_uriSpec.lastIndexOf(':', end);
                index = (colonIndex > start) ? colonIndex : end;
                hasPort = (index != end);
            }
        }
        host = p_uriSpec.substring(start, index);
        int port = -1;
        if (host.length() > 0) {
            // port
            if (hasPort) {
                index++;
                start = index;
                while (index < end) {
                    index++;
                }
                String portStr = p_uriSpec.substring(start, index);
                if (portStr.length() > 0) {
                    // REVISIT: Remove this code.
                    /** for (int i = 0; i < portStr.length(); i++) {
                      if (!isDigit(portStr.charAt(i))) {
                        throw new MalformedURIException(
                             portStr +
                             " is invalid. Port should only contain digits!");
                      }
                    }**/
                    // REVISIT: Remove this code.
                    // Store port value as string instead of integer.
                    try {
                        port = Integer.parseInt(portStr);
                        if (port == -1)
                            --port;
                    } catch (NumberFormatException nfe) {
                        port = -2;
                    }
                }
            }
        }

        if (isValidServerBasedAuthority(host, port, userinfo)) {
            m_host = host;
            m_port = port;
            m_userinfo = userinfo;
            return true;
        }
        // Note: Registry based authority is being removed from a
        // new spec for URI which would obsolete RFC 2396. If the
        // spec is added to XML errata, processing of reg_name
        // needs to be removed. - mrglavas.
        else if (isValidRegistryBasedAuthority(p_uriSpec)) {
            m_regAuthority = p_uriSpec;
            return true;
        }
        return false;
    }

    /**
     * Determines whether the components host, port, and user info
     * are valid as a server authority.
     *
     * @param host the host component of authority
     * @param port the port number component of authority
     * @param userinfo the user info component of authority
     *
     * @return true if the given host, port, and userinfo compose
     * a valid server authority
     */
    private boolean isValidServerBasedAuthority(String host, int port, String userinfo) {

        // Check if the host is well formed.
        if (!isWellFormedAddress(host)) {
            return false;
        }

        // Check that port is well formed if it exists.
        // REVISIT: There's no restriction on port value ranges, but
        // perform the same check as in setPort to be consistent. Pass
        // in a string to this method instead of an integer.
        if (port < -1 || port > 65535) {
            return false;
        }

        // Check that userinfo is well formed if it exists.
        if (userinfo != null) {
            // Userinfo can contain alphanumerics, mark characters, escaped
            // and ';',':','&','=','+','$',','
            int index = 0;
            int end = userinfo.length();
            char testChar = '\0';
            while (index < end) {
                testChar = userinfo.charAt(index);
                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(userinfo.charAt(index + 1)) || !isHex(userinfo.charAt(index + 2))) {
                        return false;
                    }
                    index += 2;
                } else if (!isUserinfoCharacter(testChar)) {
                    return false;
                }
                ++index;
            }
        }
        return true;
    }

    /**
     * Determines whether the given string is a registry based authority.
     *
     * @param authority the authority component of a URI
     *
     * @return true if the given string is a registry based authority
     */
    private boolean isValidRegistryBasedAuthority(String authority) {
        int index = 0;
        int end = authority.length();
        char testChar;

        while (index < end) {
            testChar = authority.charAt(index);

            // check for valid escape sequence
            if (testChar == '%') {
                if (index + 2 >= end || !isHex(authority.charAt(index + 1)) || !isHex(authority.charAt(index + 2))) {
                    return false;
                }
                index += 2;
            }
            // can check against path characters because the set
            // is the same except for '/' which we've already excluded.
            else if (!isPathCharacter(testChar)) {
                return false;
            }
            ++index;
        }
        return true;
    }

    /**
     * Initialize the path for this URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     * @param p_nStartIndex the index to begin scanning from
     *
     * @exception MalformedURIException if p_uriSpec violates syntax rules
     */
    private void initializePath(String p_uriSpec, int p_nStartIndex) throws MalformedURIException {
        if (p_uriSpec == null) {
            throw new MalformedURIException("Cannot initialize path from null string!");
        }

        int index = p_nStartIndex;
        int start = p_nStartIndex;
        int end = p_uriSpec.length();
        char testChar = '\0';

        // path - everything up to query string or fragment
        if (start < end) {
            // RFC 2732 only allows '[' and ']' to appear in the opaque part.
            if (getScheme() == null || p_uriSpec.charAt(start) == '/') {

                // Scan path.
                // abs_path = "/"  path_segments
                // rel_path = rel_segment [ abs_path ]
                while (index < end) {
                    testChar = p_uriSpec.charAt(index);

                    // check for valid escape sequence
                    if (testChar == '%') {
                        if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1)) || !isHex(p_uriSpec.charAt(index + 2))) {
                            throw new MalformedURIException("Path contains invalid escape sequence!");
                        }
                        index += 2;
                    }
                    // Path segments cannot contain '[' or ']' since pchar
                    // production was not changed by RFC 2732.
                    else if (!isPathCharacter(testChar)) {
                        if (testChar == '?' || testChar == '#') {
                            break;
                        }
                        throw new MalformedURIException("Path contains invalid character: " + testChar);
                    }
                    ++index;
                }
            } else {

                // Scan opaque part.
                // opaque_part = uric_no_slash *uric
                while (index < end) {
                    testChar = p_uriSpec.charAt(index);

                    if (testChar == '?' || testChar == '#') {
                        break;
                    }

                    // check for valid escape sequence
                    if (testChar == '%') {
                        if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1)) || !isHex(p_uriSpec.charAt(index + 2))) {
                            throw new MalformedURIException("Opaque part contains invalid escape sequence!");
                        }
                        index += 2;
                    }
                    // If the scheme specific part is opaque, it can contain '['
                    // and ']'. uric_no_slash wasn't modified by RFC 2732, which
                    // I've interpreted as an error in the spec, since the
                    // production should be equivalent to (uric - '/'), and uric
                    // contains '[' and ']'. - mrglavas
                    else if (!isURICharacter(testChar)) {
                        throw new MalformedURIException("Opaque part contains invalid character: " + testChar);
                    }
                    ++index;
                }
            }
        }
        m_path = p_uriSpec.substring(start, index);

        // query - starts with ? and up to fragment or end
        if (testChar == '?') {
            index++;
            start = index;
            while (index < end) {
                testChar = p_uriSpec.charAt(index);
                if (testChar == '#') {
                    break;
                }
                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1)) || !isHex(p_uriSpec.charAt(index + 2))) {
                        throw new MalformedURIException("Query string contains invalid escape sequence!");
                    }
                    index += 2;
                } else if (!isURICharacter(testChar)) {
                    throw new MalformedURIException("Query string contains invalid character: " + testChar);
                }
                index++;
            }
            m_queryString = p_uriSpec.substring(start, index);
        }

        // fragment - starts with #
        if (testChar == '#') {
            index++;
            start = index;
            while (index < end) {
                testChar = p_uriSpec.charAt(index);

                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1)) || !isHex(p_uriSpec.charAt(index + 2))) {
                        throw new MalformedURIException("Fragment contains invalid escape sequence!");
                    }
                    index += 2;
                } else if (!isURICharacter(testChar)) {
                    throw new MalformedURIException("Fragment contains invalid character: " + testChar);
                }
                index++;
            }
            m_fragment = p_uriSpec.substring(start, index);
        }
    }

    /**
     * Get the scheme for this URI.
     *
     * @return the scheme for this URI
     */
    public String getScheme() {
        return m_scheme;
    }

    /**
     * Get the scheme-specific part for this URI (everything following the
     * scheme and the first colon). See RFC 2396 Section 5.2 for spec.
     *
     * @return the scheme-specific part for this URI
     */
    public String getSchemeSpecificPart() {
        final StringBuilder schemespec = new StringBuilder();

        if (m_host != null || m_regAuthority != null) {
            schemespec.append("//");

            // Server based authority.
            if (m_host != null) {

                if (m_userinfo != null) {
                    schemespec.append(m_userinfo);
                    schemespec.append('@');
                }

                schemespec.append(m_host);

                if (m_port != -1) {
                    schemespec.append(':');
                    schemespec.append(m_port);
                }
            }
            // Registry based authority.
            else {
                schemespec.append(m_regAuthority);
            }
        }

        if (m_path != null) {
            schemespec.append((m_path));
        }

        if (m_queryString != null) {
            schemespec.append('?');
            schemespec.append(m_queryString);
        }

        if (m_fragment != null) {
            schemespec.append('#');
            schemespec.append(m_fragment);
        }

        return schemespec.toString();
    }

    /**
     * Get the userinfo for this URI.
     *
     * @return the userinfo for this URI (null if not specified).
     */
    public String getUserinfo() {
        return m_userinfo;
    }

    /**
    * Get the host for this URI.
    *
    * @return the host for this URI (null if not specified).
    */
    public String getHost() {
        return m_host;
    }

    /**
     * Get the port for this URI.
     *
     * @return the port for this URI (-1 if not specified).
     */
    public int getPort() {
        return m_port;
    }

    /**
     * Get the registry based authority for this URI.
     *
     * @return the registry based authority (null if not specified).
     */
    public String getRegBasedAuthority() {
        return m_regAuthority;
    }

    /**
     * Get the authority for this URI.
     *
     * @return the authority
     */
    public String getAuthority() {
        final StringBuilder authority = new StringBuilder();
        if (m_host != null || m_regAuthority != null) {
            authority.append("//");

            // Server based authority.
            if (m_host != null) {

                if (m_userinfo != null) {
                    authority.append(m_userinfo);
                    authority.append('@');
                }

                authority.append(m_host);

                if (m_port != -1) {
                    authority.append(':');
                    authority.append(m_port);
                }
            }
            // Registry based authority.
            else {
                authority.append(m_regAuthority);
            }
        }
        return authority.toString();
    }

    /**
     * Get the path for this URI (optionally with the query string and
     * fragment).
     *
     * @param p_includeQueryString if true (and query string is not null),
     *                             then a "?" followed by the query string
     *                             will be appended
     * @param p_includeFragment if true (and fragment is not null),
     *                             then a "#" followed by the fragment
     *                             will be appended
     *
     * @return the path for this URI possibly including the query string
     *         and fragment
     */
    public String getPath(boolean p_includeQueryString, boolean p_includeFragment) {
        final StringBuilder pathString = new StringBuilder(m_path);

        if (p_includeQueryString && m_queryString != null) {
            pathString.append('?');
            pathString.append(m_queryString);
        }

        if (p_includeFragment && m_fragment != null) {
            pathString.append('#');
            pathString.append(m_fragment);
        }
        return pathString.toString();
    }

    /**
     * Get the path for this URI. Note that the value returned is the path
     * only and does not include the query string or fragment.
     *
     * @return the path for this URI.
     */
    public String getPath() {
        return m_path;
    }

    /**
     * Get the query string for this URI.
     *
     * @return the query string for this URI. Null is returned if there
     *         was no "?" in the URI spec, empty string if there was a
     *         "?" but no query string following it.
     */
    public String getQueryString() {
        return m_queryString;
    }

    /**
     * Get the fragment for this URI.
     *
     * @return the fragment for this URI. Null is returned if there
     *         was no "#" in the URI spec, empty string if there was a
     *         "#" but no fragment following it.
     */
    public String getFragment() {
        return m_fragment;
    }

    /**
     * Set the scheme for this URI. The scheme is converted to lowercase
     * before it is set.
     *
     * @param p_scheme the scheme for this URI (cannot be null)
     *
     * @exception MalformedURIException if p_scheme is not a conformant
     *                                  scheme name
     */
    public void setScheme(String p_scheme) throws MalformedURIException {
        if (p_scheme == null) {
            throw new MalformedURIException("Cannot set scheme from null string!");
        }
        if (!isConformantSchemeName(p_scheme)) {
            throw new MalformedURIException("The scheme is not conformant.");
        }

        m_scheme = p_scheme.toLowerCase();
    }

    /**
     * Set the userinfo for this URI. If a non-null value is passed in and
     * the host value is null, then an exception is thrown.
     *
     * @param p_userinfo the userinfo for this URI
     *
     * @exception MalformedURIException if p_userinfo contains invalid
     *                                  characters
     */
    public void setUserinfo(String p_userinfo) throws MalformedURIException {
        if (p_userinfo == null) {
            m_userinfo = null;
            return;
        } else {
            if (m_host == null) {
                throw new MalformedURIException("Userinfo cannot be set when host is null!");
            }

            // userinfo can contain alphanumerics, mark characters, escaped
            // and ';',':','&','=','+','$',','
            int index = 0;
            int end = p_userinfo.length();
            char testChar = '\0';
            while (index < end) {
                testChar = p_userinfo.charAt(index);
                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_userinfo.charAt(index + 1)) || !isHex(p_userinfo.charAt(index + 2))) {
                        throw new MalformedURIException("Userinfo contains invalid escape sequence!");
                    }
                } else if (!isUserinfoCharacter(testChar)) {
                    throw new MalformedURIException("Userinfo contains invalid character:" + testChar);
                }
                index++;
            }
        }
        m_userinfo = p_userinfo;
    }

    /**
     * <p>Set the host for this URI. If null is passed in, the userinfo
     * field is also set to null and the port is set to -1.</p>
     *
     * <p>Note: This method overwrites registry based authority if it
     * previously existed in this URI.</p>
     *
     * @param p_host the host for this URI
     *
     * @exception MalformedURIException if p_host is not a valid IP
     *                                  address or DNS hostname.
     */
    public void setHost(String p_host) throws MalformedURIException {
        if (p_host == null || p_host.length() == 0) {
            if (p_host != null) {
                m_regAuthority = null;
            }
            m_host = p_host;
            m_userinfo = null;
            m_port = -1;
            return;
        } else if (!isWellFormedAddress(p_host)) {
            throw new MalformedURIException("Host is not a well formed address!");
        }
        m_host = p_host;
        m_regAuthority = null;
    }

    /**
     * Set the port for this URI. -1 is used to indicate that the port is
     * not specified, otherwise valid port numbers are  between 0 and 65535.
     * If a valid port number is passed in and the host field is null,
     * an exception is thrown.
     *
     * @param p_port the port number for this URI
     *
     * @exception MalformedURIException if p_port is not -1 and not a
     *                                  valid port number
     */
    public void setPort(int p_port) throws MalformedURIException {
        if (p_port >= 0 && p_port <= 65535) {
            if (m_host == null) {
                throw new MalformedURIException("Port cannot be set when host is null!");
            }
        } else if (p_port != -1) {
            throw new MalformedURIException("Invalid port number!");
        }
        m_port = p_port;
    }

    /**
     * <p>Sets the registry based authority for this URI.</p>
     *
     * <p>Note: This method overwrites server based authority
     * if it previously existed in this URI.</p>
     *
     * @param authority the registry based authority for this URI
     *
     * @exception MalformedURIException it authority is not a
     * well formed registry based authority
     */
    public void setRegBasedAuthority(String authority) throws MalformedURIException {

        if (authority == null) {
            m_regAuthority = null;
            return;
        }
        // reg_name = 1*( unreserved | escaped | "$" | "," |
        //            ";" | ":" | "@" | "&" | "=" | "+" )
        else if (authority.length() < 1 || !isValidRegistryBasedAuthority(authority) || authority.indexOf('/') != -1) {
            throw new MalformedURIException("Registry based authority is not well formed.");
        }
        m_regAuthority = authority;
        m_host = null;
        m_userinfo = null;
        m_port = -1;
    }

    /**
     * Set the path for this URI. If the supplied path is null, then the
     * query string and fragment are set to null as well. If the supplied
     * path includes a query string and/or fragment, these fields will be
     * parsed and set as well. Note that, for URIs following the "generic
     * URI" syntax, the path specified should start with a slash.
     * For URIs that do not follow the generic URI syntax, this method
     * sets the scheme-specific part.
     *
     * @param p_path the path for this URI (may be null)
     *
     * @exception MalformedURIException if p_path contains invalid
     *                                  characters
     */
    public void setPath(String p_path) throws MalformedURIException {
        if (p_path == null) {
            m_path = null;
            m_queryString = null;
            m_fragment = null;
        } else {
            initializePath(p_path, 0);
        }
    }

    /**
     * Append to the end of the path of this URI. If the current path does
     * not end in a slash and the path to be appended does not begin with
     * a slash, a slash will be appended to the current path before the
     * new segment is added. Also, if the current path ends in a slash
     * and the new segment begins with a slash, the extra slash will be
     * removed before the new segment is appended.
     *
     * @param p_addToPath the new segment to be added to the current path
     *
     * @exception MalformedURIException if p_addToPath contains syntax
     *                                  errors
     */
    public void appendPath(String p_addToPath) throws MalformedURIException {
        if (p_addToPath == null || p_addToPath.trim().length() == 0) {
            return;
        }

        if (!isURIString(p_addToPath)) {
            throw new MalformedURIException("Path contains invalid character!");
        }

        if (m_path == null || m_path.trim().length() == 0) {
            if (p_addToPath.startsWith("/")) {
                m_path = p_addToPath;
            } else {
                m_path = "/" + p_addToPath;
            }
        } else if (m_path.endsWith("/")) {
            if (p_addToPath.startsWith("/")) {
                m_path = m_path.concat(p_addToPath.substring(1));
            } else {
                m_path = m_path.concat(p_addToPath);
            }
        } else {
            if (p_addToPath.startsWith("/")) {
                m_path = m_path.concat(p_addToPath);
            } else {
                m_path = m_path.concat("/" + p_addToPath);
            }
        }
    }

    /**
     * Set the query string for this URI. A non-null value is valid only
     * if this is an URI conforming to the generic URI syntax and
     * the path value is not null.
     *
     * @param p_queryString the query string for this URI
     *
     * @exception MalformedURIException if p_queryString is not null and this
     *                                  URI does not conform to the generic
     *                                  URI syntax or if the path is null
     */
    public void setQueryString(String p_queryString) throws MalformedURIException {
        if (p_queryString == null) {
            m_queryString = null;
        } else if (!isGenericURI()) {
            throw new MalformedURIException("Query string can only be set for a generic URI!");
        } else if (getPath() == null) {
            throw new MalformedURIException("Query string cannot be set when path is null!");
        } else if (!isURIString(p_queryString)) {
            throw new MalformedURIException("Query string contains invalid character!");
        } else {
            m_queryString = p_queryString;
        }
    }

    /**
     * Set the fragment for this URI. A non-null value is valid only
     * if this is a URI conforming to the generic URI syntax and
     * the path value is not null.
     *
     * @param p_fragment the fragment for this URI
     *
     * @exception MalformedURIException if p_fragment is not null and this
     *                                  URI does not conform to the generic
     *                                  URI syntax or if the path is null
     */
    public void setFragment(String p_fragment) throws MalformedURIException {
        if (p_fragment == null) {
            m_fragment = null;
        } else if (!isGenericURI()) {
            throw new MalformedURIException("Fragment can only be set for a generic URI!");
        } else if (getPath() == null) {
            throw new MalformedURIException("Fragment cannot be set when path is null!");
        } else if (!isURIString(p_fragment)) {
            throw new MalformedURIException("Fragment contains invalid character!");
        } else {
            m_fragment = p_fragment;
        }
    }

    /**
     * Determines if the passed-in Object is equivalent to this URI.
     *
     * @param p_test the Object to test for equality.
     *
     * @return true if p_test is a URI with all values equal to this
     *         URI, false otherwise
     */
    @Override
    public boolean equals(Object p_test) {
        if (p_test instanceof URI) {
            URI testURI = (URI) p_test;
            if (((m_scheme == null && testURI.m_scheme == null) || (m_scheme != null && testURI.m_scheme != null && m_scheme.equals(testURI.m_scheme))) && ((m_userinfo == null && testURI.m_userinfo == null) || (m_userinfo != null && testURI.m_userinfo != null && m_userinfo.equals(testURI.m_userinfo))) && ((m_host == null && testURI.m_host == null) || (m_host != null && testURI.m_host != null && m_host.equals(testURI.m_host))) && m_port == testURI.m_port && ((m_path == null && testURI.m_path == null) || (m_path != null && testURI.m_path != null && m_path.equals(testURI.m_path))) && ((m_queryString == null && testURI.m_queryString == null) || (m_queryString != null && testURI.m_queryString != null && m_queryString.equals(testURI.m_queryString))) && ((m_fragment == null && testURI.m_fragment == null) || (m_fragment != null && testURI.m_fragment != null && m_fragment.equals(testURI.m_fragment)))) {
                return true;
            }
        }
        return false;
    }

    @Override
    public int hashCode() {
        int hash = 5;
        hash = 47 * hash + Objects.hashCode(this.m_scheme);
        hash = 47 * hash + Objects.hashCode(this.m_userinfo);
        hash = 47 * hash + Objects.hashCode(this.m_host);
        hash = 47 * hash + this.m_port;
        hash = 47 * hash + Objects.hashCode(this.m_path);
        hash = 47 * hash + Objects.hashCode(this.m_queryString);
        hash = 47 * hash + Objects.hashCode(this.m_fragment);
        return hash;
    }

    /**
     * Get the URI as a string specification. See RFC 2396 Section 5.2.
     *
     * @return the URI string specification
     */
    @Override
    public String toString() {
        final StringBuilder uriSpecString = new StringBuilder();

        if (m_scheme != null) {
            uriSpecString.append(m_scheme);
            uriSpecString.append(':');
        }
        uriSpecString.append(getSchemeSpecificPart());
        return uriSpecString.toString();
    }

    /**
     * Get the indicator as to whether this URI uses the "generic URI"
     * syntax.
     *
     * @return true if this URI uses the "generic URI" syntax, false
     *         otherwise
     */
    public boolean isGenericURI() {
        // presence of the host (whether valid or empty) means
        // double-slashes which means generic uri
        return (m_host != null);
    }

    /**
     * Returns whether this URI represents an absolute URI.
     *
     * @return true if this URI represents an absolute URI, false
     *         otherwise
     */
    public boolean isAbsoluteURI() {
        // presence of the scheme means absolute uri
        return (m_scheme != null);
    }

    /**
     * Determine whether a scheme conforms to the rules for a scheme name.
     * A scheme is conformant if it starts with an alphanumeric, and
     * contains only alphanumerics, '+','-' and '.'.
     *
     * @return true if the scheme is conformant, false otherwise
     */
    public static boolean isConformantSchemeName(String p_scheme) {
        if (p_scheme == null || p_scheme.trim().length() == 0) {
            return false;
        }

        if (!isAlpha(p_scheme.charAt(0))) {
            return false;
        }

        char testChar;
        int schemeLength = p_scheme.length();
        for (int i = 1; i < schemeLength; ++i) {
            testChar = p_scheme.charAt(i);
            if (!isSchemeCharacter(testChar)) {
                return false;
            }
        }

        return true;
    }

    /**
     * Determine whether a string is syntactically capable of representing
     * a valid IPv4 address, IPv6 reference or the domain name of a network host.
     * A valid IPv4 address consists of four decimal digit groups separated by a
     * '.'. Each group must consist of one to three digits. See RFC 2732 Section 3,
     * and RFC 2373 Section 2.2, for the definition of IPv6 references. A hostname
     * consists of domain labels (each of which must begin and end with an alphanumeric
     * but may contain '-') separated & by a '.'. See RFC 2396 Section 3.2.2.
     *
     * @return true if the string is a syntactically valid IPv4 address,
     * IPv6 reference or hostname
     */
    public static boolean isWellFormedAddress(String address) {
        if (address == null) {
            return false;
        }

        int addrLength = address.length();
        if (addrLength == 0) {
            return false;
        }

        // Check if the host is a valid IPv6reference.
        if (address.startsWith("[")) {
            return isWellFormedIPv6Reference(address);
        }

        // Cannot start with a '.', '-', or end with a '-'.
        if (address.startsWith(".") || address.startsWith("-") || address.endsWith("-")) {
            return false;
        }

        // rightmost domain label starting with digit indicates IP address
        // since top level domain label can only start with an alpha
        // see RFC 2396 Section 3.2.2
        int index = address.lastIndexOf('.');
        if (address.endsWith(".")) {
            index = address.substring(0, index).lastIndexOf('.');
        }

        if (index + 1 < addrLength && isDigit(address.charAt(index + 1))) {
            return isWellFormedIPv4Address(address);
        } else {
            // hostname      = *( domainlabel "." ) toplabel [ "." ]
            // domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
            // toplabel      = alpha | alpha *( alphanum | "-" ) alphanum

            // RFC 2396 states that hostnames take the form described in
            // RFC 1034 (Section 3) and RFC 1123 (Section 2.1). According
            // to RFC 1034, hostnames are limited to 255 characters.
            if (addrLength > 255) {
                return false;
            }

            // domain labels can contain alphanumerics and '-"
            // but must start and end with an alphanumeric
            char testChar;
            int labelCharCount = 0;

            for (int i = 0; i < addrLength; i++) {
                testChar = address.charAt(i);
                if (testChar == '.') {
                    if (!isAlphanum(address.charAt(i - 1))) {
                        return false;
                    }
                    if (i + 1 < addrLength && !isAlphanum(address.charAt(i + 1))) {
                        return false;
                    }
                    labelCharCount = 0;
                } else if (!isAlphanum(testChar) && testChar != '-') {
                    return false;
                }
                // RFC 1034: Labels must be 63 characters or less.
                else if (++labelCharCount > 63) {
                    return false;
                }
            }
        }
        return true;
    }

    /**
     * <p>Determines whether a string is an IPv4 address as defined by
     * RFC 2373, and under the further constraint that it must be a 32-bit
     * address. Though not expressed in the grammar, in order to satisfy
     * the 32-bit address constraint, each segment of the address cannot
     * be greater than 255 (8 bits of information).</p>
     *
     * <p><code>IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT</code></p>
     *
     * @return true if the string is a syntactically valid IPv4 address
     */
    public static boolean isWellFormedIPv4Address(String address) {

        int addrLength = address.length();
        char testChar;
        int numDots = 0;
        int numDigits = 0;

        // make sure that 1) we see only digits and dot separators, 2) that
        // any dot separator is preceded and followed by a digit and
        // 3) that we find 3 dots
        //
        // RFC 2732 amended RFC 2396 by replacing the definition
        // of IPv4address with the one defined by RFC 2373. - mrglavas
        //
        // IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
        //
        // One to three digits must be in each segment.
        for (int i = 0; i < addrLength; i++) {
            testChar = address.charAt(i);
            if (testChar == '.') {
                if ((i > 0 && !isDigit(address.charAt(i - 1))) || (i + 1 < addrLength && !isDigit(address.charAt(i + 1)))) {
                    return false;
                }
                numDigits = 0;
                if (++numDots > 3) {
                    return false;
                }
            } else if (!isDigit(testChar)) {
                return false;
            }
            // Check that that there are no more than three digits
            // in this segment.
            else if (++numDigits > 3) {
                return false;
            }
            // Check that this segment is not greater than 255.
            else if (numDigits == 3) {
                char first = address.charAt(i - 2);
                char second = address.charAt(i - 1);
                if (!(first < '2' || (first == '2' && (second < '5' || (second == '5' && testChar <= '5'))))) {
                    return false;
                }
            }
        }
        return (numDots == 3);
    }

    /**
     * <p>Determines whether a string is an IPv6 reference as defined
     * by RFC 2732, where IPv6address is defined in RFC 2373. The
     * IPv6 address is parsed according to Section 2.2 of RFC 2373,
     * with the additional constraint that the address be composed of
     * 128 bits of information.</p>
     *
     * <p><code>IPv6reference = "[" IPv6address "]"</code></p>
     *
     * <p>Note: The BNF expressed in RFC 2373 Appendix B does not
     * accurately describe section 2.2, and was in fact removed from
     * RFC 3513, the successor of RFC 2373.</p>
     *
     * @return true if the string is a syntactically valid IPv6 reference
     */
    public static boolean isWellFormedIPv6Reference(String address) {

        int addrLength = address.length();
        int index = 1;
        int end = addrLength - 1;

        // Check if string is a potential match for IPv6reference.
        if (!(addrLength > 2 && address.charAt(0) == '[' && address.charAt(end) == ']')) {
            return false;
        }

        // Counter for the number of 16-bit sections read in the address.
        int[] counter = new int[1];

        // Scan hex sequence before possible '::' or IPv4 address.
        index = scanHexSequence(address, index, end, counter);
        if (index == -1) {
            return false;
        }
        // Address must contain 128-bits of information.
        else if (index == end) {
            return (counter[0] == 8);
        }

        if (index + 1 < end && address.charAt(index) == ':') {
            if (address.charAt(index + 1) == ':') {
                // '::' represents at least one 16-bit group of zeros.
                if (++counter[0] > 8) {
                    return false;
                }
                index += 2;
                // Trailing zeros will fill out the rest of the address.
                if (index == end) {
                    return true;
                }
            }
            // If the second character wasn't ':', in order to be valid,
            // the remainder of the string must match IPv4Address,
            // and we must have read exactly 6 16-bit groups.
            else {
                return (counter[0] == 6) && isWellFormedIPv4Address(address.substring(index + 1, end));
            }
        } else {
            return false;
        }

        // 3. Scan hex sequence after '::'.
        int prevCount = counter[0];
        index = scanHexSequence(address, index, end, counter);

        // We've either reached the end of the string, the address ends in
        // an IPv4 address, or it is invalid. scanHexSequence has already
        // made sure that we have the right number of bits.
        return (index == end) || (index != -1 && isWellFormedIPv4Address(address.substring((counter[0] > prevCount) ? index + 1 : index, end)));
    }

    /**
     * Helper method for isWellFormedIPv6Reference which scans the
     * hex sequences of an IPv6 address. It returns the index of the
     * next character to scan in the address, or -1 if the string
     * cannot match a valid IPv6 address.
     *
     * @param address the string to be scanned
     * @param index the beginning index (inclusive)
     * @param end the ending index (exclusive)
     * @param counter a counter for the number of 16-bit sections read
     * in the address
     *
     * @return the index of the next character to scan, or -1 if the
     * string cannot match a valid IPv6 address
     */
    private static int scanHexSequence(String address, int index, int end, int[] counter) {

        char testChar;
        int numDigits = 0;
        int start = index;

        // Trying to match the following productions:
        // hexseq = hex4 *( ":" hex4)
        // hex4   = 1*4HEXDIG
        for (; index < end; ++index) {
            testChar = address.charAt(index);
            if (testChar == ':') {
                // IPv6 addresses are 128-bit, so there can be at most eight sections.
                if (numDigits > 0 && ++counter[0] > 8) {
                    return -1;
                }
                // This could be '::'.
                if (numDigits == 0 || ((index + 1 < end) && address.charAt(index + 1) == ':')) {
                    return index;
                }
                numDigits = 0;
            }
            // This might be invalid or an IPv4address. If it's potentially an IPv4address,
            // backup to just after the last valid character that matches hexseq.
            else if (!isHex(testChar)) {
                if (testChar == '.' && numDigits < 4 && numDigits > 0 && counter[0] <= 6) {
                    int back = index - numDigits - 1;
                    return (back >= start) ? back : (back + 1);
                }
                return -1;
            }
            // There can be at most 4 hex digits per group.
            else if (++numDigits > 4) {
                return -1;
            }
        }
        return (numDigits > 0 && ++counter[0] <= 8) ? end : -1;
    }

    /**
     * Determine whether a char is a digit.
     *
     * @return true if the char is betweeen '0' and '9', false otherwise
     */
    private static boolean isDigit(char p_char) {
        return p_char >= '0' && p_char <= '9';
    }

    /**
     * Determine whether a character is a hexadecimal character.
     *
     * @return true if the char is betweeen '0' and '9', 'a' and 'f'
     *         or 'A' and 'F', false otherwise
     */
    private static boolean isHex(char p_char) {
        return (p_char <= 'f' && (fgLookupTable[p_char] & ASCII_HEX_CHARACTERS) != 0);
    }

    /**
     * Determine whether a char is an alphabetic character: a-z or A-Z
     *
     * @return true if the char is alphabetic, false otherwise
     */
    private static boolean isAlpha(char p_char) {
        return ((p_char >= 'a' && p_char <= 'z') || (p_char >= 'A' && p_char <= 'Z'));
    }

    /**
     * Determine whether a char is an alphanumeric: 0-9, a-z or A-Z
     *
     * @return true if the char is alphanumeric, false otherwise
     */
    private static boolean isAlphanum(char p_char) {
        return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_ALPHA_NUMERIC) != 0);
    }

    /**
     * Determine whether a character is a reserved character:
     * ';', '/', '?', ':', '@', '&', '=', '+', '$', ',', '[', or ']'
     *
     * @return true if the string contains any reserved characters
     */
    private static boolean isReservedCharacter(char p_char) {
        return (p_char <= ']' && (fgLookupTable[p_char] & RESERVED_CHARACTERS) != 0);
    }

    /**
     * Determine whether a char is an unreserved character.
     *
     * @return true if the char is unreserved, false otherwise
     */
    private static boolean isUnreservedCharacter(char p_char) {
        return (p_char <= '~' && (fgLookupTable[p_char] & MASK_UNRESERVED_MASK) != 0);
    }

    /**
     * Determine whether a char is a URI character (reserved or
     * unreserved, not including '%' for escaped octets).
     *
     * @return true if the char is a URI character, false otherwise
     */
    private static boolean isURICharacter(char p_char) {
        return (p_char <= '~' && (fgLookupTable[p_char] & MASK_URI_CHARACTER) != 0);
    }

    /**
     * Determine whether a char is a scheme character.
     *
     * @return true if the char is a scheme character, false otherwise
     */
    private static boolean isSchemeCharacter(char p_char) {
        return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_SCHEME_CHARACTER) != 0);
    }

    /**
     * Determine whether a char is a userinfo character.
     *
     * @return true if the char is a userinfo character, false otherwise
     */
    private static boolean isUserinfoCharacter(char p_char) {
        return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_USERINFO_CHARACTER) != 0);
    }

    /**
     * Determine whether a char is a path character.
     *
     * @return true if the char is a path character, false otherwise
     */
    private static boolean isPathCharacter(char p_char) {
        return (p_char <= '~' && (fgLookupTable[p_char] & MASK_PATH_CHARACTER) != 0);
    }

    /**
     * Determine whether a given string contains only URI characters (also
     * called "uric" in RFC 2396). uric consist of all reserved
     * characters, unreserved characters and escaped characters.
     *
     * @return true if the string is comprised of uric, false otherwise
     */
    private static boolean isURIString(String p_uric) {
        if (p_uric == null) {
            return false;
        }
        int end = p_uric.length();
        char testChar = '\0';
        for (int i = 0; i < end; i++) {
            testChar = p_uric.charAt(i);
            if (testChar == '%') {
                if (i + 2 >= end || !isHex(p_uric.charAt(i + 1)) || !isHex(p_uric.charAt(i + 2))) {
                    return false;
                } else {
                    i += 2;
                    continue;
                }
            }
            if (isURICharacter(testChar)) {
                continue;
            } else {
                return false;
            }
        }
        return true;
    }
}
